Errata for View Updating and Relational Theory

The errata list is a list of errors and their corrections that were found after the product was released. If the error was corrected in a later version or reprint the date of the correction will be displayed in the column titled "Date Corrected".

The following errata were submitted by our customers and approved as valid errors by the author or editor.

"As this latter view is a projection of a restriction, we can infer the effects of updates on it by invoking Date’s rules for updating through projection to determine the effects on the underlying restriction, then invoke the rules for updating though restriction to determine the effects on the underlying base relvar S.
Date, C. J. (2012-12-20). View Updating and Relational Theory (Kindle Locations xvi). O'Reilly Media. Kindle Edition.
though s/b through

"Personally I do think views should be supported, for reasons Iï¿½ll explain in the section Data Independence on page 34; further, ...
Date, C. J. (2012-12-20). View Updating and Relational Theory (Kindle Locations 1178-1179). O'Reilly Media. Kindle Edition.
Page 34? I still have my vinyl records and paper books so maybe it is just me and the fact that this is my second Kindle book but I don't see any page 34 using a Kindle Reader. soon, or following, and drop the page number?

Note from the Author or Editor:The reference to page 34 was added by the copyeditor! It's OK for the printed book. I'm sure it's nonsense in the Kindle version, but I don't have access to that.

"It follows that we must solve this problem, for otherwise we have to give up on the goal of data independence. (Logical ...
Date, C. J. (2012-12-20). View Updating and Relational Theory (Kindle Locations 1232-1233). O'Reilly Media. Kindle Edition.
The "mus" in must is italicized but the "t" is not.

Kevin Davis

Feb 15, 2013

Other Digital Version

Kindle Locations 1282-1284
just before How Not to do it in Ch 3

Second, (a) the mapping between a view and the relvars in terms of which itï¿½s defined should be specified separately and concealed from the user, just as (b) the mapping between a base relvar and physical storage already is specified separately and concealed from the user.
Date, C. J. (2012-12-20). View Updating and Relational Theory (Kindle Locations 1282-1284). O'Reilly Media. Kindle Edition.
Strange nit. On the Kindle version the "(a) the" has the expected space following the rt. paren but "(b) the" appears as "(b)the" for all font resizings. I wonder how this looks in the print version? Interesting that the Kindle copy and Windows paste into this buffer shows the requisite space. I'm regretting having purchased the Kindle version in an aesthetic sense. In a practical sense there is lot less drat and bother when it comes to providing feedback.

Note from the Author or Editor:I wasn't involved in producing the Kindle version and have no access to it.

It will often be the case that the compensatory actions can be stated in a variety of syntactically distinct but semantically equivalent forms. For example, the delete rule from S to LS and NLS — ON DELETE d FROM S : DELETE ( d WHERE CITY = 'London' ) FROM LS , DELETE ( d WHERE CITY &#8838; 'London' ) FROM NLS ;
Date, C. J. (2012-12-20). View Updating and Relational Theory (Kindle Locations 1801-1806). O'Reilly Media. Kindle Edition.
subset? I.e. this part is, only, a reference to the prior:
ON DELETE d FROM S : DELETE ( d WHERE CITY = 'London' ) FROM LS , DELETE ( d WHERE CITY &#8800; 'London' ) FROM NLS ;
Date, C. J. (2012-12-20). View Updating and Relational Theory (Kindle Locations 1780-1783). O'Reilly Media. Kindle Edition.
P.S. I did notice that two of my posts have been removed (disjoint union cf. math disjoint union; seeming conflict with views and security). With all due humility, what's with that? This O'Reilly errata page led me to believe that "Question or Request for Clarification" was a reasonable submission. And elsewhere the author has solicited ideas on this topic so I trust that, although I may at times be, a wee bit, strident, I am not out of bounds.

Note from the Author or Editor:In the 3rd bullet point, the Kindle version shows:
DELETE ( d WHERE CITY &#8838; 'London' ) FROM NLS ;
Instead of:
DELETE ( d WHERE CITY &#8800; 'London' ) FROM NLS ;

Kevin Davis

Feb 26, 2013

Other Digital Version

Kindle Locations 1868-1869
Kindle Locations 1868-1869

One reviewer of an early draft of this book asked why, in the example of relvars S, LS, and NLS, the compensatory actions all had to be cascades. To be specific, he ï¿½ the reviewer was male ï¿½
Date, C. J. (2012-12-20). View Updating and Relational Theory (Kindle Locations 1868-1869). O'Reilly Media. Kindle Edition.
I just don't know what to make of that!

Note from the Author or Editor:A bit of political correctness, that's all.

Note from the Author or Editor:There's a bug here but the suggested fix is wrong. The correct fix is: Delete the closing parenthesis before the colon at the end of line 3.

Kevin Davis

Feb 27, 2013

Other Digital Version

Kindle Locations 1942-1945
Kindle Locations 1942-1945

nit ".Note" in:
The existing tuple for supplier S2 is deleted from relvar NLS and a new tuple for that supplier, with CITY value Oslo, is inserted into that same relvar. .Note: I assume for simplicity here (and in examples throughout the book, wherever it’s helpful to do so) that we can talk in terms of deleting and inserting individual tuples as such, rather than relations. Technically, however, you should understand such talk as referring to sets of tuples, where the sets in question just happen to have cardinality one.
Date, C. J. (2012-12-20). View Updating and Relational Theory (Kindle Locations 1942-1945). O'Reilly Media. Kindle Edition.

Kevin Davis

Feb 27, 2013

Other Digital Version

Kindle Locations 1961-1964
Kindle Locations 1961-1964

An attempt is made to insert a new tuple for supplier S2, with CITY value London, into relvar NLS. That attempt fails, however, because it violates the constraint on relvar NLS that the CITY value in that relvar can never be London. So the update fails overall; the previous step (viz., deleting the original tple for supplier S2 from NLS) is undone, and the net effect is that the database remains unchanged.
Date, C. J. (2012-12-20). View Updating and Relational Theory (Kindle Locations 1961-1964). O'Reilly Media. Kindle Edition.
tple s/b tuple

Kevin Davis

Feb 27, 2013

Other Digital Version

Kindle Locations 3413-3418
Kindle Locations 3413-3418

In the Kindle edition there is a ï¿½White Sun With Raysï¿½ as the JD symbol between the SCP: and the line starting with {{SNO.:
ï¿½Actually I donï¿½t think thereï¿½s all that much to be said. Recall from Chapter 5 that if DB1 contains just a single relvar R and DB2 contains just projections of R, then DB1 and DB2 are information equivalent only if those projections are obtained by decomposing R in accordance with some join dependency (JD) that holds in R. Well, the following JD does hold in SCP:
<a white sun with rays with white background instead of the asterisk against the page sepia background I expected> { { SNO , CITY } , { PNO , CITY } }
Date, C. J. (2012-12-20). View Updating and Relational Theory (Kindle Locations 3413-3418). O'Reilly Media. Kindle Edition.
I appreciate beautiful mathematical and physics texts and I would have likely passed over the symbols flamboyance if it were not for the fact that the background for the symbol is white instead of the full page sepia background. In An Intro to Database Systems: 8th Ed. there is an asterisk with a hollow center for JD but it is still an asterisk. In The Relational Database Dictionary an asterisk is used. In Logic and Databases. the white sun with rays is used. My recollection of other JD denotations involve an asterisk. With all due respect, this reader is not a fan of the white sun with rays!
http://www.fileformat.info/info/unicode/char/263c/index.htm
Knowing this book has unfortunate differences between media types I was inclined to mention this symbol difference and to also express my appreciation to Don Knuth for his motivations for TeX.
A punter, I be! a pedant, maybe?

Note from the Author or Editor:But I quite like it. It's not important.

2. Suppose we delete all tuples for supplier S1 from relvar SP. The effect will be to delete all tuples for supplier S1 from relvar SSP and also to delete the tuple (S1,20) from relvar S.
Date, C. J. (2012-12-20). View Updating and Relational Theory (Kindle Locations 3612-3613). O'Reilly Media. Kindle Edition.
20 s/b London

Kevin Davis

Mar 08, 2013

Other Digital Version

Kindle Locations 3617-3619
Kindle Locations 3617-3619

6. Suppose we delete the tuple (S1,20) from relvar S. The effect will be to delete all tuples for supplier S1 from relvar SSP. Of course, the rule governing deletes on SSP will now come into play, which will (not unreasonably) have the effect of deleting all tuples for supplier S1 from relvar SP as well.
Date, C. J. (2012-12-20). View Updating and Relational Theory (Kindle Locations 3617-3619). O'Reilly Media. Kindle Edition.
20 s/b London

Kevin Davis

Mar 08, 2013

Other Digital Version

Kindle Locations 3639-3642
Kindle Locations 3639-3642

A concrete example of a database value satisfying the foregoing conditions can be obtained by extending Figure ï¿½ 8-1 to reinstate the usual tuple for supplier S5 (see Figure ï¿½ 8-2 overleaf, and observe in particular that the relations shown as the current values of relvar SP and SSP in that figure are the same as they were in Figure ï¿½ 8-1).
Date, C. J. (2012-12-20). View Updating and Relational Theory (Kindle Locations 3639-3642). O'Reilly Media. Kindle Edition.
As remarked previously by the author regarding an explicit printed page number, I know that 'overleaf' is likewise inapplicable in the Kindle edition but I take liberty to mention it since so far there is not a preponderance of these kind of constructs and to have none should be considered. (Or is it that I'm annoyed that I didn't buy a paper edition?)

Note from the Author or Editor:When I wrote this book I didn't even know there was going to be a Kindle edition. All such Kindle-specific comments will be acted on in future writings.